Azimuth circle



Noma, 1936. B. M. GREEN` 2,059,944

AZIMUTH CIRCLE Filed Feb. 28, 1935 4 Sheets-Sheet l v l I 3 wro/z Green www@ NOV. 3, 1936. B, M GREEN 2,059,944

v AZIMUTH CIRCLE Filed Feb. 28, 1955 4 Sheets-Sheet 2 5 Z4 I n I r I (y /9 0 /0 I /Z i l NOV. 3, 1936. B; M GREEN 2,059,944

AZ IMUTH CIRCLE Filed Feb. 28, 1955 4 sheets-sheet s M eelt.

B. M. GREEN AZIMUTH CIRCLE Nov. 3, 1936;

Filed Feb. 28, 1955 4 Sheets-Sheet 4 Patented Nov. 3, 1936 i UNiTEo sTATEs PATENT oEEicE nunon M. oma'nmklyp. N. Y. application February 28, 1935, .Serial No. 8,145 v 14 claims. (ci. ss-zs) reading is shown by one reilectingmeans while My present invention relates to azimuth circles, and particularly to instruments of the type and character set forth in my Patent No. 2,028,063, January 14, 1936.

An object of this invention is to provide an azimuth or bearing circle to be associated with a mariners, navigators, surveyors, or other compass. and to be used in taking bearings at sea as an aid to navigation, on land as for surveying, in the ileld to determine the position of an airship, aeroplane or other moving object, and in other connections where observations, bearings and readings are desired to be determined in connection with celestial and terrestrial bodies and objects, at all angles above the vhorizon up to the zenith, and at various anglesbelow the horizon.

A further object is to provide an instrument of this character which includes leveling-means interposed to be shown directly in the field of vision with compass card readings to vthus permit most accurate adjustment oi the instrument to follow and to maintain a level coinciding with the natural horizon, while at the same time following or retaining in view thel body or object upon which the instrument is being trained.

A still further object resides in so constructing and arranging the parts that the compass card the body or object can be caught in reected image in another reflecting means, and in so mounting the second reflecting means that it can be adjusted to a position entirely out of the field of the iirst reiiecting means to thus permit free and unobstructed direct sighting.

Another object is to provide a reilecting prism to show compass card and level readings and a second reflecting prism to show images of the body or object upon which the instrument is trained, and in so mounting the, second prisml that it can be adjusted Ato focus in and reiiect the desired image, and in all positions of adjustf ment the second prism will be closely adjacent to and substantially overlapping in the iield of vision with the apex of theiirst prism.

' Still another object and purpose is tol provide a compass reflecting prismthat does not require the use of readily deteriorated silver or reflecting coatings, and which will reflect compass-card readings and level indicating readings without inversion.

Yet another purpose is to provide an instrument which includes front and rear sights, in addition to the reilecting means, and which can thus be very accurately and closely focused upon the body or object.

With the above andother objects in view,

which will be apparent to those skilled in the art. my present invention includes certain novel features of construction and combinations of parts, and improvements, which will be herein-v 5 after set forth in connection with the drawings.

In the drawings: Figure 1 is a view in perspective illustrating one adaptation of my present invention as it illustrate the disposition of the parts and to indicate some possible adjustments of the focusing prism.

Fig. 6 is a fragmentary illustration in elevation to show the view as it will appear through the sight when the structure is in use.

Fig. 7 is a broken sectional view to better illus- 25 trate one of the bearings for mounting ofthe image reector.

Fig. 8 is a fragmentary detail view to better v show the front sight. so Fig. 9-is a fragmentary View of the rear sight.

understood that the invention is adaptable for n application to and use with substantially any and all types and constructions of compasses, surveying instruments and other instruments employing or including a compass or other direc- .tional indicating structure.

The compass structure, generally indicated at l, and which as hereinbefore stated can be of any desired type or construction, has a ring 2 mounted thereon for revoluble movement in a -normally horizontal plane, a flange 3 being pro- 50 vided to retain the ring in place, and the center of the ring being preferably fully open to give a free and unobstructed view of the compass card I.

A rear sight 5 is hingedly mounted at 6, on one 55 side of the ring, and is provided with an elongat'ed sight slit T extending substantially at right angles to the plane of rotation of the ring 2.

This sight slit may be provided at desired points 5 with one or more peep openings 3, to thus designate particular elevations along the length of the isht slit- 1.

A supporting frame work 9 is mounted on the ring 2, by means of screws I0 or other suitable 10 fastenings, and is thus rigidly held at a point substantially diametrically opposite to the mounting of the sight 5. This supporting bracket structure 9 has side plates II extending in spaced relation inwardly therefrom, and a back plate I2 extends across between these side plates II and is disposed substantially at an angle of .'forty-ilve degrees from the horizontal. A compass card reflecting prism I3 is positioned between the side plates II and is protected by the back plate I2. This prism I3 is of pentagonal shape, and is of the double reecting type. The face I4 of prism I 3 is adjacent to and in a plane substantially parallel with the normal plane of the compass card 4, and the objective face I 5 of the prism is disposed to show the reected image in a substantially perpendicular plane, or in other words at an angle of substantially ninety degrees to the plane of the compass card. This prism I3 is made to be of the double reflecting type, and consequently will show image reflections of the compass card without inversion. Further, by reason of the form of the prism it is not necessary to silver or otherwise coat any of the faces of the prism I3 to accomplish full and clear reflection of the image in upright and proper relation. To protect the prism I3, and to maintain this prism in proper position, a mounting frame I6 is provided to fit upon the faces of the prism opposite the face covered by the back .40 plate I2, and this mounting frame or shield plate structure is held in place by the use of screws I1, or other. suitable fastenings.

The side plates II extend beyond the image face I5 of the prism I3, further toward the center ofthe circle or ring 2, and a front sight I8 is pivotally mounted between these extension portions. This front sight has an elongated and relatively wide sight opening I9 therethrough, and a hair sight line 20 is provided for fine and accurate viewing. It is desirable that this front sight I8 be pivotally mounted so that it can be swung' down adjacent to the cover glass of the compass to thus be lbelow the line of sight when observations are taken through the rear sight 5, without use of the front sight.

With this arrangement, the ring or circle 2 can be applied to a compass and can be turned and adjusted to permit the instrument to be lined or focused, through the lfront vand rear sights 5,-

'30 and I3, upon a celestial or terrestrial body or object, and the effective portion of the compass card will then be reflected in image in the objective face I5 of the prism I3, the hair line 20 of the front sight serving to bisect the image portion of the compass to permit an accurate and close reading of the compass indication. The front sight I8 can be made sufciently long to permitl ings as generally indicated at 22, and preferably at al1 times be mamtaiii constructed after the manner illustrated in Fig. 7. A substantially U-shaped prism mounting frame 23 has a three sided prism 24,'here shown as a substantially equilateral triangular prism, mounted and carried therein with its lower apex angle substantially parallel with the upper apex angle ofthe prism I3. This U-shaped frame is provided with trunnion pins 25 which are disposed with their axes of rotation on the lower side of the apex angle of prism 24, and these bearing l. trunnions 25 are iournalled in the bearings 22 so that as hand wheels 28 on the ends of the trunnion shafts 25 are manipulated the U-shaped frame 23 and consequently the prism 24 will be swung and will be adjusted, for focusing and for u other purposes, with respect to the prism I3. Due to the placement of the trunnion shafts 25, the entire prism structure 24 is bodily swung with respect to the upper apex angle of prism I3, and in consequence the lower angle of prism 24 is at 2. all times maintained in close proximity to, or is slightly below a horizontal line taken through the upper apex angle of prism I3. In this way, there is at no time any appreciable separation or space between the adjustable external object prism 24 and the apex angle of the objective face I5 of the prism I3. With this construction, there Is substantially no possibility or likelihood that any external object can be seen through a space between the two prisms, and it is possible to draw 30 the external object or body reflection more clearly and closely into focus and into the proximated field of vision with the compass card reflection. as viewed through the sights in the objective face I5 of the prism I3. The front and rear sights I3 35 and 5 function and serve to permit accurate focusing and centering of the reection of the external body or image as caught and brought into the eld of i vision by the prism 24.

It is essential that the adjustable prism 24 shall n l ed to swing upon a substantially horizontal axis, and that adjustments of the prism 24 when once made shall be retained until the partsare further manipulated and adjusted by the user. With this in mind, the u bearings 22 are provided with bearing recesses to receive and Ycenter the trunnion or pintle shaft portions 25, and with'blocks 21 to retain the portions 25 within the bearing recesses. These blocks 21 are secured in place by means of screws 28, or 5.

other suitable fastenings, and are retained in position by pins 29. Tension washers 30 are preferably provided to insure that uniform tension will be maintained upon the trunnion or pintle shafts 25 and that adjustments of the focusing prism `55 24 will be frictionally held and maintained.

As has been stated, it is essential that the image as focused into the prism 24 be brought closely into the field of vision with the reflection of the' compass card, and it is also essential that level n indicating readings be brought into this same field of vision so that in substance three observations and readings can be made simultaneously, namely a reading to show that the circle or ring 2 is disposed in `substantially horizontal relation in a plane with the true horizon, a reading showing the reflected image of the body or objectas focused in the prism 24, and a reading showing the effective portion of the compass card. It is essential that the ring or circle 2 must be absolutely 70 l level when the image of the object or body is seen centered in the prism 24 and when the reading of the compass card is taken, and with instruments as heretofore constructed, it has been extremely difficult to make accurate readings due to 75 "the feet that oftentimes the eye must be directed particularly to the level indicating means and then the line of vision must be varied to see .the reflected image of the body or object as focused, and perhaps the line of sight must be shifted a third time to see the compass card reading. Obviously such shifting of the line of sight and such distraction from any one of the three essential indications willtend toward inaccuracy in the nal bearing or other reckoning, and it is one of the primary purposes of my invention to provide an instrument in which the level indication is at all times shown substantially transposed upon the effective part of the compass card as reflected, and the image upon which the instrument is trained or focused will be also so closely adjacent to the compass card reading that there can be little likelihood for error orinaccuracies in the readings. n

With the above in mind, I mount an open level 3|, perhaps preferably of the tubular bubble oil ner, and the'level indication will thus be reflected through the prism .I3 to be shown transposed upon the reflected portion of the compass card, and th'e level indication can b'e at all times.. kept fully in view Without shifting the line of vision or distracting from a full view of the focusing prism 24. i

Where the prism 24 is being adjusted to focus in a celestial body of the second or lesser magnitude, or tol give an image of any obscure or small terrestrial indication or mark, the vision, and consequently the use and eflciency of the instrument, may be improved by providing a suitable magnifying glass or lens 33 on the front sight I8. This aid to vision can be of any desired type, and can be carried by frame portion 34 to be adjustable vertically uponthe front sight I8, a set screw 35, or other means, being suitably provided to hold adjustments thereof.

As has been stated, in some u'ses the prism 24 will be swung out of the line of sight, and in this relation the prism will be substantially folded down against the back plate- I2. If desired, a

vshield or spring clip cover 3B, as' shown in Fig.

10 can be provided to be fitted over the upper edges of the side plates II, and the prism 24 is then protected from accumulation of moisture, dirt, or other foreign substances.

At night, where an' illuminated compass is used, the effective portion of the compass card will be very clearly caught and reflected by the prism I3, and as the level indicating means 3| is of the opentube type, the light will readily penetrate to show this leveling means fully and clearly in the image visible at the objective face I5 of the prism. However, the light of the com: pass may interfere with effective and efficient focusing upon celestial bodies of lesser magni tude, upon. dim shore lights, and upon other bodies or objects from which bearings are desired to be taken. With this in mind, I provide a cover structure, one form of which is illustratediin Fig. 11. closes over the major portion of the top of the compass, and the substantially semi-circular body portio-n 31 is shaped and constructed to be fitted upon the ring 2, and is provided with suitable notches or recesses 38 to accommodate the front sight 5. This body portion 31 has at its center a bearing 39, and the segment-shaped shield members 40 and 4I arepivotally and adjusted into and out of positions. for use.

.both `of the sights.

A5 here shown, the cover swingably mounted onthis bearing portion 39, by means of pin 42 or other suitable pivotal means. These segment-shaped shield plates 40 and 4I are notched orrecessed at 42 and 43 to accommodate the supporting portion 9 and thesenotched or recessed formations are preferably so shaped that the edges of the segment-shaped shield portions 4I) and 4I will llt closely adjacent to the prism supporting structure. It may be found desirable to provide upturned rim flanges 44 around therecesses 42 and 43 and to provide interfltting flange portions 45 at adjacent edges of the two shield members 40 andl 4I where they meet, and at the edge of the body portion 31, where this terminates adjacent to the shield members. The body portion 31 can be provided 'with clip portions to be sprung over the ring 2,

or screws or other suitable fastenings can be employed to mount the body portion in place. With this shield and cover structure it is possbleto open either of the shield members 40 or 4I, or both, so that the compass card can be viewed, or all portions can be closed and light will then be held in and rain, dust, spray, and ihe like will be excluded, the flange formations at 44 and 4.5 serving effectively to turn back water which might otherwise drive or' seep through between the several members and parts.

This. cover willbe found most useful on dark nights when watching the bearing of lights espe. cially on approaching vessels in close quarters,

as it blanks out the illuminatedface of the com-A pass and allows only the compass field in the effective area to become visible in the lower prism; and, at the Sametime this'elimination of the light from the face of the compassvand the consequent prevention of effusion of light from the top of the compass very materiallyl aids the eye when bringing celestial bodies down to the plane of sight in the object prism. With this covery the effusion of light from the top of the compass is excluded without diminishing the illumination of the effective portion of the compass ileld under the prism, and at the same time the Waterproof features of the cover shield the compass glassfrom exposure to damage.-

The usual shade glasses 46 and 41 can'be lmounted in the manner shown, or in any other desiredmanner, to be available to be shifted and Also, as an aid in excluding external light and the like various well known shade of shield structures can be fitted in connection with either orv It is usual and customary to provide counterbalance weights and frictional I brake or drag means upon the ring 2 s o -that the balanceof the compass upon its gimbals or .other supports will not be disturbed, and that adjustments of the ring when revolved upon the compass structure will be maintained, and I have therefore not here particularly described such structure. Also, handle portions can be providedupon the ring' to permit more ready turning movement thereof.

In some instances it may be found advisable to omit the ring 2, and to provide in lieu thereof legs or supporting feet adapted to rest upon the glass or the rim of the compass case, and to be positioned and guided in their rotational movement by the rim', or by other suitable portions of the cbmpass case or structure. Further, the prismatic structure can be made and be supplied for application to or 'mounting upon a ring, or other' sight as being l of peep sight construction, and have particularly shown the front sight as al hair sight, but varying conditions may necessitate changes in the type of sight employed in each instance. In some instances it will be found desirable to use the instrument without the front sight Il, and focusing can then be accomplished through the grooved sight 2| in the upper edge of the back plate l2, and the focusing will thus be substantially at the upper apex edge of the obejective face i5 of the compass deilecting prism I3. For more convenient use in this manner it is desirable that the front sight i8 be made of such length that it will fold down between its pivotal mounting and the mounting of the rear sight 5,

and then this forward sight i8 is entirely below, .the ileld of vision and will not in any way interfere with or obstruct the use of the rear sight and other portions. In some instances it may be found necessary or desirable to cut or otherwise mark a sight line upon one or both of the prism's Il and 24, to serve substantially the same purpose as is accomplished by the hair strand or wire 20 of the front sight I8.

While I have illustrated only certain specific embodiments of my present invention, and have referred to only certain possible other adaptations and constructions, it will be appreciated that many changes and variations can be made in the form, construction, arrangement, assembly, mounting, association, use, adjustment and operation of the parts, without departing from the spirit and scope of my invention.

I claim:

1., With a ring to be associated with a compass and revoluble in a substantially horizontal plane, a sight carried by said ring for viewing radially with respect to the compass, level indicating means carried by the ring opposite said sight, and a pentagpnal-shaped prism disposed to be viewed through the sight and constructed to show juxtapositioned reections of the leveling means and the compass card in the same field of vision and in a line diametrically across the ring from the sight.

2. With a ring to be associated with a compass and revoluble in a substantially horizontal plane, a sight carried by said ring for viewing radially with respect to the compass, level indicating means carried by the ring opposite said sight, a pentagonal-shaped prism disposed to be viewed through the sight and constructed to show juxtapositioned reilections of the leveling means' and the compass card in the same ileld of vision and in a line diametrically across the ring from the sight, and a reflecting prism adjustably mounted to swing on a substantially horizontal axis im- `mediately adjacent to the iirst mentioned prisline with the sight to reflect in correct reading relation an image of a portion of the compass card immediately in the diametrical line of sight and at the same time to show an interposed image of the leveling means in the same eld of vision.

4. With a ring to be associated with a compass and revoluble in a substantially horizontal plane, a sight carried by said ring for viewing substan- 'tially horizontally and radially with respect to/V the compass, level indicating means carried by the ring opposite said sight,'a pentagonal-shaped prism disposed to be viewed through the sight and constructed to show juxtapositioned reflections of the leveling means and the compass card in the same field of vision and in a line diametrically across the ring from the sight, and a second sight means disposed intermediate the rst sight means and the reflecting parts to thus permit more accurate centering upon the image.

5. With a compass, a ring revolubly associated with the compass, a sight carried by said ring at one side, leveling means carried by the ring diametrically opposite the sight, a single five-sided prism carried by the ring in line with the sight to reect an image of a portion of the compass card immediately in the diametrical line of sight and at the same time to show an interposed image of the leveling means in the same field of vision, and a substantially triangular prism swingably mounted upon a horizontal axis eccentrically centered with respect to the apex angle of the plane, a sight carried by said ring for viewing radially with respect to the compass, level indicating means carried by the ring opposite said sight, a single pentagonal-shaped double reilecting prism disposed to be viewed through the sightand constructed to show juxtapositioned reflections of the leveling means and the compass card in the same eld of vision and in a line diametrically across the ring from the sight, a

reflecting prism adjustably mounted to swing on -a substantially horizontal axis immediately adjacent to the rst mentioned prismatic means to catch and reflect showing of an external image also closely adjacent to and within the line of sight with the reflections of the compass and level reading, and resilient tension means to maintain proper centering and retain adjustments of the swingable adjustable prism.

7. With a compass, a single pentagonal reectirig prism having an objective face readable diametrically across the compass card to show an indicating portion of the compass card, and level indicating means interposed to be shown upon the image of the compass card reflected in the objective face of the prism.

8. The combination, with a compass and an azimuth circle, of a single prism to show readings oi a compass card without reversal, a second prism swingably and substantially eccentrically mounted ladjacent to the apex angle of the objective face of the first compass for adjustable movement to catch and reflect an image upon which a focus is to be taken, the second prism due to its eccentric mounting being at all times positioned to allow the focused image to be drawn down closely adjacent to the apex angle of the compass reilecting prism, and level indicating means positionedin the field of the first prism to be shown interposed over the showing of the compass card.

9. With a compass, a three-sided prism to refleet external image, a ve-sided prism closely adjacent to the ilrst prism to reflect in the same iield of vision and without reversal a compass reading, and level indicating means positioned to be reected in the second prism and shown in interposed relation upon thev compass field.

10. With a compass, a prism to reflect external image, a second prism closely adjacent to the first prism to reflect in the same field of vision a compass reading, a front sight directed toward said prisms, and a single rear sight interposed between the prisms and the front sight to establish a line for focusing and viewing reflection in both of said prisms.

1l. Withy a compass, a ring fitted around the face of the compass, and cover structure carried by said ring provided with substantially segmental swingably mounted members to be moved back to expose the face of the compass therebeneath.

l2. An apparatus for taking bearings cornpris'ing, a compass, a ring revolubly associated with said compass, a sight carried at one side of said ring, a reflector associated-with said ring at a point substantially diametrically opposite to said sight to reflect readings of the compass, level means interposed over the face of the compass to transpose a reflection of said leveling means adjacent to the reflected readings of the compass, and a second reflector associated with said ring at a fixed location 'immediately adjacent to and Within the eld of vision with said first reector as viewed through the sight and adjustably held to permit focusing of an image adjacent to the reflected compass reading.

13. An apparatus for taking bearings comprising, a compass, a ring revolubly associated with said compass, a sight carried at one side of s aid ring, a reflector associated with said ring at a point substantially diametrically opposite to said sight to-reect readings of the compass,

' level means interposed over the face of the compass to transpose a reection of said leveling means adjacent to the reflected readings of the compass, a second reflector associated with said ring at a fixed location immediately adjacent to and Within the eld -of vision with said first reflector as viewed through the sight and adjustably held to permit focusing of animage adjacent to the reflected compass reading, and a second sight interposed in front of the sight as carried at one side of the ring to serve as 'a center for focusing and reading of the reflections in both of the reflectors.

14. With a compass, a supporting ring fitted around the compass, a cover portion carried by the ring to cover non-effective portions of the face of the compass, and segmental-shaped cover portions swingably mounted on said rst mentioned cover portion to be swung to closed positions to cover the effective portion of the face of the compass and to opened positions to permit viewing of this porti-on of the face of the compass.

BURTON M. GREEN. 

